Electrical conductor cable



pril 8 1924.

T. VARNEY ELECTRICAL CONDUCTOR CABLE Filed July 2. 1920 Flush WIT/VESSES Patented pr. 8, 1924.

UNITED STATES l 1,489,402 PATENTV OFFICE.-

THEODORE VABNEY, OF SEWICKLEY, PENNSYLVANIA, ASSIGN'OR T0 ALUMINM COMPANY 0F AMERICA,` 0F PITTSBURGH, PENNSYLVANIA, A. CORPORATION 0F PENNSYLVANIA.

ELECTRICAL CONDUCTOR CABLE.

Application lcd .Tuly 2,

To all whom t may concern:

Be it known that I, THEoDoRn VARNEY, a citizen of the United States, residing at Sewickley in the county of Allegheny and State of lennsylvania, have invented certain-new and useful Improvements in Electrical Conductor Cab1es,'of which the following is a specification.

My invention relates to electrical conductors, and more particularly to a flexible velectrical conductor cable designed for the transmission of electrical power by means of very high voltages.

Commercial high tension transmission cables have heretofore nerally consisted of copper strands, aluminum strands, or a combination of high strength steel strands with aluminum, and while such cables have proven satisfactory under certain conditions of service as re ards the corona, in cases 'where the lines o not employ, for example, over one hundred and twentysfive thousand volts, they are not capable of carrying, without considerable loss, higher voltages.

It has been found by experience and research (as is well known to those familiar with the art) that when a voltage exceeds a certain critical value for a conductor of a certain diameter, the air in the vicinity of the wire commences to breakdown and electricity leaks from the cable into the surrounding air, thereby producing a loss 4of power. This is known as corona oss. yWhen a certain transmission line, therefore, has reached its limit of carrying capacity, -it would be possible to carry more power over that line if the voltage of the line could be increased. This cannot be done, however. beyond a certain critical value 'without in-Y creasing the diameter of the cable.

In order to prevent corona loss, it is not necessary to increase the cross section of the conducting material, but'it is necessary to increase the overall diameter of the cable. Furthermore, this increase of diameter should, ifpossible, not be attended by an increase. of weight, because the limit of the strength of the towers, insulators, and fittings which support the cable would have to be, correspondingly increased if the weight of the cable were increased.

For commercial purpose, it is necessary that the cable should possess a degree yof flexibility sufficient to enable it to be wound upon reels or drums, the size of the drums,

1920. Serial No. 393,503.

of course, depending upon the size and weight of the cable. For instance, a cable embodying my invention may have an outside diameter of two inches or moreand a cable of this size would preferably have to be capable of bending ina circle having a radius of about twelve inches.

The prime object of my invention is to provide a new and improved electrical conductor possessing the required strength and flexibility and capable of effective use. in high tension transmissionlines employing very high voltages.

In the accompanying drawings, which illustrate applications of my invention,

Fig. 1 is a side elevational view of a portion of a flexible electrical conductor cable embodying my invention;

Fig. 2, a cross sectional view of the form of Fig. 1; and

Figs. y3, 4 and 5, cross sectional views of modified forms of my invention.

Referring to the drawings, and first to the form of Fig. l, 2 designates a flexible tube or tubing preferably formedr of a suitable metal, for example, galvanized steel, aluminum, or other metals; or, if preferred, the tubing may be non-metallic. The tubing employed should be of such a character as to give resistance to transverse crushing, and should have sufficient longitudinal strength to enable the tubing to pass through stranding machinery and to withstand the usual amount of handling during the process of installation. The principal function of the tubing is to provide an increased diameter to the conductor cable over that possible with an equal weight and longitudinal strength produced by a solid bundle of wires.

. As illustrated in the formof Fig. 1, the flexible tubing is surrounded by a plurality of layers of wires or members 3; while the wires or members surrounding the tubing may be composed of any material havin the desired qual-ities, I prefer to employ igh strength galvanized steel for these longitudinally extending cable strengthening means.the function of the wires 3 bein to provide the requisite longitudina strength;

Surrounding the wires 3 I provide a plurality of layers of wires or members .4, composed of a material possessing high electrical conductivity; i. e., aluminum or copper,

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YVhile I have shown two layers of strengthening wires and three layers of electrical conducting wires in the form of Fig. 1, it is obvious that I may employ a single layer of wire having a high tensile strength and a single layer of wire of good conductivity or that the wires designed for the purposes specied may be differently assembled, it' being desired that an annular conducting casing preferably formed of contacting strands of naked wire be provided.

The forms of Figs. 3 and et show the arrangement of placing the longitudinal strengthening wires 3 within the flexible tubing 2a and the conducting wires 4.- outside of the said tubing. The longitudinal wires in this case form a stranded cable in themselves and may or may not fill the interior of the tubing In Fig. 3, the space between the interior walls of the flexible tube and the wires 2a is completely or partially filled with a brous braid 5, this braid being placed on the stranded wires or enclosed cable 3 prior to its being drawn into the tubing. In place of the braid 5, an insulating covering known commercially as weatherproof insulation could be employed. The wires or stranded cable 3" may be employed as in Fig. 4 without a covering or material between said cable and the interior Walls of tubing 2a. In each of the forms of Figs. 3 and 4, one or more layers of electrical conductive wires 4 are positioned on the outer surface of the tubing.

In the form of Fig. 5 I dispense with the strengthening wires and rely upon the longitudinal strength of the electrical conductor 4b, the latter preferably including one or more layers of wires of high electrical conductivity surrounding the flexible tubing 2".

By means of the constructions herein shown and described, a cable of considerable overall diameter capable of eiliciently takin care of corona loss in circuits havin vo tages as high as two hundred and fifty thousand, or even more, is provided.

It will be noted that the embodiments of myI invention contemplate a cable having an overall cross sectional area considerably greater than the cross sectional area of the conductor per se, thus obviating the corona loss; further, by the employment of the flexible tubing, the weight of the cable is kept -down to a minimum.

What I claim is:

l. An aerial conductor cable havin alarge over-all cross-sectional area relative y to its metallic area andincluding` a flexible metal tubing, longitudinal strengthening wires whose combined cross sectional area isconsiderably less than the area of a circle whose diameter is that of the cable, and an annular outer surface of high electric conductivity.

2. An electrical conductor cable including a flexible supporting tubing inherently capable of resisting relatively high transverse pressures, longitudinal strengthening means, and an annular outer surface of high electrical conductivity embracing the tubing and strengthening means.

3. An electrical conductor cable including a flexible tubing inherently capable of resisting transverse pressures, and an annular outer series of contacting strands of high electrical conductivity embracing the flexible tubing, and longitudinal strengthening means enclosed within the conducting strands.

4. An electrical conductor cable including a flexible tubing inherently capable of resisting transverse pressures, longitudinal strengthening wires surrounding the tubing, and an annular series of contacting conducting wires of high electrical conductivity surrounding the first mentioned wires or strands and exposed to the atmosphere.

5. An electrical conductor cable including a flexible galvanized steel tubing, 1ongitudinal strengthening wires Wound around said tubing, andan outer annular series of contacting wires of high electrical conductivity wound upon the longitudinal strengthening wires.

6. An aerial conductor cable for high tension currents comprising a stranded conductor having enclosed within it ahollow core and longitudinal strengthening Wires of high tensile strength, the cross sectional area of the metal in the cable bein considerably less than the area of a circ e whose diameter is the over-all diameter of the cable. l

7. An aerial electric conductor cable for high tension currents including a flexible tubing inherently capable of withstanding relatively high transverse pressures an adapted to be bent to a re atively sharp g curvature withoutl deformation thereof, longitudinal strengthening wires, and annular means surroun ing the outside of the tubing and outside of the strengthening wires having a high electrical conductivity.

8. An aerial electric conductor cable having a small over-all cross sectional area of metal relatively to the diameter of the conductor, and including an outer annular conductor of electricity, the conductivit of which is high, a relatively thin light tu ing `within the conductor capable of resisting` transverse pressures and inherently capable of supporting rthe conductor, and longitudinally extending means having a high tensile strength enclosed within the conductor, the cross sectional area of the conductor strengthening means and tubing be- .ing considerably less than the area of s.

circle, the diameter of which is the over-all diameter of the cable.

'high electric conductivity, longitudinally extending strengthening means having a high tensile stren th enclosed within the casing, and a flexib e tubing Within the conductor inherently capable of holding the conductor from being collapsed, this construction enablin the conductor to have a. relatively large iameter with a minimum cross sectional area of metal, the cross sectional area of the conductor strengthening means and ltubing being considerably lessl than the area of a circle whose diameter is that of the `cable.

10. An' aerial cable for high tension currents comprisin an annular stranded conductor of a hig electric conductivity having a relatively large diameter With a. relatively small cross sectional area of' metal,k longitudinally extending strengtheninfr meanshaving a high tensile stren th Within the conductor, and a relatively t in flexible metal tubing serving as a sup ort for the conductor and preventing it rom` .collapsing and which is inherently capable of resisting relatively high transverse pressures. v

11. An aerial conductor for high tension currents comprising an annular strandedl conductor having a high electric conductivity, longitudinal strengthenin means of high tensile strength enclosed tlierewithin, and spirally Wound flexible tubingk for supporting the conductor and preventing it from collapsing. Y

12. An aerial cable for high tension currents comprising a flexible tubing formed of spirally Wound substantially flat thin sheet metal land inherently capable of Withstanding relatively high transverse presn sures, and a stranded `conductor surround ing the tubing and supported thereon.

In testimony whereof I aix my signature in presence of two Witnesses.

THEGDORE VARNEY. Witnesses:

` J. M. GEOGHEGAN,

Lois WINEMAN. 

